Power storage apparatuses such as a secondary battery and an electric double layer capacitor (condenser) have conventionally been used as batteries in hybrid vehicles and electric vehicles. In the power storage apparatuses, the battery performance may be reduced or the battery life may be shortened due to heat generation of the battery or the like in charge and discharge.
To address this, a proposal has been made in which a power storage apparatus is cooled by supplying air or the like for cooling to a case which houses the power storage apparatus. Another proposal is to fill a cooling fluid into a sealed container which houses an assembled battery including a plurality of connected battery cells or a sealed container which houses a plurality of batteries (for example, see Patent Documents 1 and 2).
Batteries (or battery cells) described in Patent Documents 1 and 2 have a structure in which a power generation element (including electrode elements and electrolyte layers) is covered with a case (made of laminated film, for example). The battery and the cooling fluid are housed in the sealed container. The cooling fluid is in contact with the case of the battery in the structure.
The case is typically sealed to prevent water or the like from entering the case. The case is filled with dry gas (for example, air or nitrogen gas) or the case is evacuated. The structure will be described with reference to FIG. 5.
In FIG. 5, a battery unit (power generation element) 100 including electrode elements and electrolyte layers is housed in a case 200. The battery unit 100 has a structure in which an electrode element for a positive electrode and an electrode element for a negative electrode are stacked with the electrolyte layer interposed therebetween. Each of the electrode elements has a collector and an electrode layer (positive electrode layer or negative electrode layer) formed on a surface of the collector.
In the cooling structures described in Patent Documents 1 and 2, the cooling fluid is in contact with the case 200 to radiate heat of the battery unit 100 (cool the battery unit 100) through the case 200.
[Patent Document 1] Japanese Patent Publication No. 11 (1999)-26031 (paragraph numbers 0031, 0034, 0035, and FIG. 1)
[Patent Document 2] Japanese Patent Publication No. 2003-346924 (paragraph numbers 0011 to 0013, and FIG. 1)